i just bought a 1990 f150 with the 5.0 302 (yeah, i went kinda old school). The truck is in awesome shape, my only problem is that it sometimes has a hard time starting, and idles kinda rough espescially right after i get done driving it somewhere. i did a tune up this weekend and four out of my eight spark plugs were covered in gasoline. seeing as how this engine is fuel injected, i'm pretty well stumped. its been a long time since i have played with these older engines and i'm quickly realizing just how much i've forgotten. any help would be great!

 

The business ends were wet? Low/lack of spark.

 

Just throwing out ideas, but are you sure the plugs are hooked up in the right firing order?

Is the timing too far advanced?

Are the plugs in the motor worn out and maybe too cold a heat range?

Is the air filter clogged?

 

On a truck that old I would look at the fuel filter, O2 sensors, air filter, plugs and wires as well as the cap and rotor to start with. That truck had electronic advance and retard timing but I would not rule it out as a problem.

 

You've got it wired wrong. Get a wiring diagram and check.

 

i forgot to mention that when i changed the plugs i also replaced cap and rotor, fuel filter, air filter. what about the fuel pressure regulator? somebody had mentioned that to me but i dont know much about them...

 

Iv had similar issues and gone through most every system, changed lots of parts. Although the truck did start running better over all, I did not completely solve the rough idle nor the large fuel consumption. The system that I have been overlooking and read in these forums that could be the issue, is the smog/ air pump system. It has all kinds of solenoids, valves and air passages that also connect to the exhaust system, it could get soot or crap from the pump clogged in places causing drivability issues. I'll do more diagnosis and check back with ya.